The present invention relates to apparatus for the ambulatory monitoring of the detrusor pressure exerted by a bladder, and more particularly to a vesicovaginal apparatus therefor.
Conventional urodynamic assessment, performed most often in the urodynamic laboratory during a brief recording time and under nonphysiologic circumstances, may fail to reveal the exact nature of existing pathologic conditions of the lower urinary tract. One of the most clinically challenging groups of patients are those who present sensory urgency as their sole symptom. Sensory urgency is defined by the International Continence Society as "urgency and frequency as apparently isolated symptoms in the absence of demonstrable detrusor contractions." In order to make the diagnosis of sensory urgency, all of the other conditions which may cause abnormal contractility of the detrusor muscle must be ruled out. These include urinary tract infection, bladder or urethral calculi, bladder tumor, neuropathic lesions, pharmacologic manipulations and intrinsic muscle dysfunction.
Urodynamic studies are utilized as a foundation to understand the pathophysiology of the lower urinary tract, and, when combined with the history and physical examination, permit accurate diagnosis and formulation of a logical treatment plan. In patients experiencing sensory urgency as their only symptom, and in whom all other pathophysiology has been ruled out, this logical progression from diagnosis to treatment is frequently interrupted as the recorded tests often fail to correlate with the patient's symptoms. These studies may fail to show detrusor reflex contractions during routine cystometry, despite various detrusor provocative maneuvers, such as coughing, alteration in position or valsalva. Continuous bladder monitoring has proven to truly be a breakthrough in the diagnosis and treatment of these patients Ambulatory monitoring studies performed thus far have revealed occult bladder instability in a substantial proportion of these patients.
Various attempts have been made to monitor changes in bladder pressure on a continuous basis, utilizing liquid or air-coupled systems as well as telemetric techniques. Solid-state microtip transducers presently offer the best reproducibility with which to obtain reliable pressure signals during ambulatory monitoring. Preliminary studies indicate that the results of continuous monitoring utilizing natural fill cystometry are consistent with the clinical history of sensory urgency and urge incontinence, whereas conventional provocative cystometric techniques may give false or negative results.
To date, ambulatory monitoring has employed an intravesical pressure or bladder situated transducer in order to measure bladder pressures directly and either a transrectal or transurethral pressure transducer as an indirect measure of intraabdominal pressure. Subtracted pressure then yields true detrusor or intrinsic bladder pressure. However, since a twenty-four transrectal monitor is used as a reflection of intraabdominal pressure measurements, fecal impaction and rectal motility can often affect the results. The transrectal monitor is uncomfortable and therefore results in low patient compliance with the instructions of the doctor. Additionally, the transrectal monitor must be removed for each defecation or passage of flatus, thereby interfering with the study and further lowering patient compliance since handling of the transrectal monitor is understandably distasteful to most patients. Thus the disadvantages of a transrectal monitor in terms of patient comfort, patient compliance, and accuracy are well known in the art and need not be set forth herein in any detail.
Intraabdominal pressure has also been measured by using a transducer situated in the proximal one third of the urethra. However, although the proximal one-third of the urethra is of intraabdominal origin and therefore reflects this pressure, smooth and striated muscle, as well as vascular, elastic and connective tissue, each exert their own influence in contributing to intrinsic urethral pressure. Accordingly, transurethral pressure measurements may not simply reflect intraabdominal pressure and are considered separate essential parameters of a complete urological workup.
In the laboratory setting, intravaginal pressure measurements have been demonstrated to reflect intraabdominal pressure more accurately and consistently than transrectal or transurethral pressure measurements, provided the sensor is positioned in the upper two-thirds of the vagina, above the urogenital diaphragm. The vagina is less subject to physiological processes than the rectum; for example, it is less subject to variation secondary to fecal impaction and rectal motility, is less subject to artificially-induced contractions, and in general undergoes less movement (at least in its upper two-thirds). A transvaginal monitor is thus not only more accurate, but results in generally higher levels of patient compliance since it need not be removed to effect evacuation and is reported to be quite comfortable to the wearer. Thus far, urodynamic studies using the vagina as an alternative to the rectum in measuring intraabdominal pressure have been performed during conventional laboratory cystometric testing, where the transvaginal transducer was taped to the patient's inner thigh and connected by trailing wires to the urodynamic equipment. James, E. D., et al., "The Vagina as an Alternative to the Rectum in Measuring Abdominal Pressure
During Urodynamic Investigations," Br.J. Urol. 60:212-16 (1987). The intravaginal catheter was held in place securely 8 cm from the introitus by a balloon inflated to 5 cc and taped to the patient's inner thigh. This has allowed catheter stability, but has not allowed patient ambulation. To date, there are no fully ambulatory studies of this kind.
Thus, the need remains to investigate the clinical, diagnostic and therapeutic capabilities of ambulatory bladder monitoring in women utilizing a transvaginal monitor as a reflection of intraabdominal pressure. Total bladder pressure will be measured directly, and true bladder pressure (detrusor pressure) will be determined by subtraction (bladder pressure minus transvaginally-determined intraabdominal pressure).
Accordingly, it is an object of the present invention to provide vesicovaginal apparatus for ambulatory monitoring of the detrusor pressure exerted by a bladder.
Another object is to provide such apparatus which avoids the disadvantages associated with transrectal or transurethral pressure determinations in terms of comfort, accuracy and patient compliance and secondary variations such as fecal impaction and rectal motility.
Another object is to provide such apparatus which is not affected by rectal motility and fecal impaction.
It is also an object of the present invention to provide such apparatus which is of simple and economical construction, and easy to maintain and use.